Towards the implementation of a preference-and uncertain-aware solver using answer set programming

Logic programs with possibilistic ordered disjunction (or LPPODs) are a recently defined logic-programming framework based on logic programs with ordered disjunction and possibilistic logic. The framework inherits the properties of such formalisms and merging them, it supports a reasoning which is nonmonotonic, preference-and uncertain-aware. The LPPODs syntax allows to specify 1) preferences in a qualitative way, and 2) necessity values about the certainty of program clauses. As a result at semantic level, preferences and necessity values can be used to specify an order among program solutions. This class of program therefore fits well in the representation of decision problems where a best option has to be chosen taking into account both preferences and necessity measures about information. In this paper we study the computation and the complexity of the LPPODs semantics and we describe the algorithm for its implementation following on Answer Set Programming approach. We describe some decision scenarios where the solver can be used to choose the best solutions by checking whether an outcome is possibilistically preferred over another considering preferences and uncertainty at the same time.Postprint (published version

Insertion of carbon dioxide and isocyanide into tantalum-amide and tantalum-methyl bonds

The methyl–amide complex [TaCp*(NtBu)Me(NMe2)] (1a) was isolated by reaction of the chloro–methyl [TaCp*(NtBu)MeCl] complex with LiNMe2. Reaction of the mono-amide compounds [TaCp*(NtBu)XY] (X=NMe2, Y=Me (1a); X=NHtBu, Y=Me (1b), Cl (1c)) with CO2 gives the η2-carbamate derivatives [TaCp*(NtBu)(η2-O2CX)Y] (X=NMe2, Y=Me (2a); X=NHtBu, Y=Me (2b), Cl (2c)). A similar reaction with the di-amide complex [TaCp*(NtBu)(NHtBu)2] (1d) gives the di-carbamate derivative [TaCp*(NtBu){η2-O2C(NHtBu)}{η1-O2C(NHtBu)] (2d). Reaction of the methyl–carbamate (2a) with isocyanide CNAr (Ar=2,6-Me2C6H3) gives the η2-iminoacyl–η1-carbamate complex [TaCp*(NtBu){η2-C(Me)NAr}{η1-O2C(NMe2)] (3a). Formation of the related compound [TaCp*(NtBu){η2-C(Me)NAr}{η1-O2C(NHtBu)}] (3b) was only detected by NMR spectroscopy in C6D6 or CDCl3 whereas the reaction of 2b in hexane gives the η1-iminoacyl–η2-carbamate complex [TaCp*(NtBu){η1-C(Me)NAr}{η2-O2C(NHtBu)}] (3b′). All of the new compounds were characterized by elemental analysis and 1H- and 13C-NMR spectroscopy

Oxo and imido/imido exchange and C-H activation reactions based on pentamethylcylopentadienyl imido tantalum complexes

Reactions of [TaCp*Cl4] with two, three and four equivalents of LiNHt Bu give the halo- and amido-imido complexes [TaCp*Cl2(Nt Bu)] (1a), [TaCp*Cl(Nt Bu)(NHt Bu)] (2) and [TaCp*(Nt Bu)(NHt Bu)2] (3), respectively. The related complex [TaCp*Cl2{N(2,6-Me2C6H3)}] (1b) is prepared by a similar reaction using two equivalents of Li[NH(2,6-Me2C6H3)]. Complex 3 can be transformed into 2 and further into 1a by reaction with SiClMe3. Complex 1a reacts with CNt Bu to give the 18-electron adduct [TaCp*Cl2(Nt Bu)(CNt Bu)] (4) whereas addition of excess CN(2,6-Me2C6H3) results in reductive elimination of the carbodiimide t BuN C N(2,6-Me2C6H3) (5) to give [TaCp*Cl2{CN(2,6-Me2C6H3)}3]. However complex 1b does not react with any of the isocyanide ligands. Both complexes 1a and 1b react with PhCHO undergoing imido/oxo exchange to give the imines PhCH NR (R=t Bu, 2,6-Me2C6H3 (6)) and dimeric [TaCp*Cl2(O)]2 or trimeric [(TaCp*Cl)3(m2-Cl)(m2-O)3(m3-O)] oxo-complexes, whereas only 1a reacts with CO2, PhCH NR% (R%=Ph, Me) and (2,6-Me2C6H3)N C Nt Bu producing t BuN CO, PhCH Nt Bu and t BuN C Nt Bu, respectively and the corresponding oxo or imido tantalum derivative. None of the complexes reacts with CO or NCR (R=Me, Ph). The complex [TaCp*Me(Nt Bu)(NHt Bu)] activates C–H bonds when heated in benzene and toluene affording [TaCp*Ph(Nt Bu)(NHt Bu)] (7) and a mixture of [TaCp*(m-MeC6H4)(Nt Bu)(NHt Bu)] 8a and [TaCp*(pMeC6H4)(Nt Bu)(NHt Bu)] (8b). All of the reported organic compounds and tantalum complexes were characterized by 1 H- and 13C-NMR spectroscopyThe authors acknowledge DGICYT (project PB97-0776) for financial support and J.S.N. acknowledges MEC for a fellowship

A preference meta-model for logic programs with possibilistic ordered disjunction

This paper presents an approach for specifying user preferences related to services by means of a preference meta-model, which is mapped to logic programs with possibilistic ordered disjunction following a Model-Driven Methodology (MDM). MDM allows to specify problem domains by means of meta-models which can be converted to instance models or other meta-models through transformation functions. In particular we propose a preference meta-model that defines an abstract preference specification language allowing users to specify preferences in a more friendly way using models. We also present a meta-model for logic programs with possibilistic order disjunction. Then we show how we conceptually map the preference meta-model to logic programs with possibilistic ordered disjunction by means of a mapping function.Peer ReviewedPostprint (published version

Synthesis and reactivity of imido niobium complexes containing the functionalized (dichloromethylsilyl)cyclopentadienyl ligand

The niobium complex [NbCpClCl4] (CpCldouble bond; length as m-dashη5-C5H4(SiCl2Me)) (1) with a functionalized (dichloromethylsilyl)cyclopentadienyl ligand was isolated by the reaction of [NbCl5] with C5H4(SiCl2Me)(SiMe3). Complex 1 was a precursor for the imido silylamido derivative [NbCpNCl2(NtBu)] (CpNdouble bond; length as m-dashη5-C5H4[SiClMe(NHtBu)]) (2) after addition of LiNHtBu, which subsequently gave the dichlorosilyl compound [NbCpClCl2(NtBu)] (3) when reacted with SiCl3Me. Addition of LiNHtBu to complex 2 gave the niobium amido complex [NbCpNCl(NHtBu)(NtBu)] (4), which slowly evolved with exchange of the niobium-amido and the silicon-chloro groups to give the dichloroniobium complex [NbCpNNCl2(NtBu)] (CpNNdouble bond; length as m-dashη5-C5H4[SiMe(NHtBu)2]) (5). Reaction of 2 with excess LiNHtBu gave the silyl-η-amido constrained geometry complexes [Nb{η5-C5H4[SiMe(NHtBu)(-η-NtBu)]}(NHtBu)(NtBu)] (6) and [Nb{η5-C5H4[SiClMe(-η-NtBu)]}(NHtBu)(NtBu)] (7), whereas addition of one equimolecular amount of LiNHtBu to 5 in C6D6 afforded complex [NbCpNNCl(NHtBu)(NtBu)] (8). All of the new complexes were characterized by 1H, 13C and 29Si NMR spectroscopy.Universidad de Alcal

Functionalization of silica with amine and ammonium alkyl chains, dendrons and dendrimers: Synthesis and antibacterial properties

Materials modified with ammonium groups on the surface have shown antibacterial activity. In this paper, alkyl chains, carbosilane (CBS) dendrimers and dendrons and poly(amidoamine) (PAMAM) dendrimers containing amine and ammonium groups have been grafted to silica surface and the influence of molecule structure on the stability and on antibacterial activity have been evaluated. These materials have been characterized by thermogravimetric analysis (TGA), zeta (Z) potential, scanning electron microscopy (SEM), infrared spectroscopy (IR) and nuclear magnetic resonance (C-13 CP MAS NMR). The degree of silica functionalization depends on type of outer groups, amine or ammonium, type and core of dendrimer, and length of chains. The Z potential measurements of these materials in water suspensions were used to test their stability in this medium. These measurements showed, for some of the modified silicas, the diminishing of Z potential from positive values toward zero, probably due to interaction of the functional groups with the silica surface. This variation was also dependent on ligand structure and peripheral functions. Finally, studies of inhibition of bacteria growth stand out again the relevance of ligand structure and number of functional groups on silica surface. The most active systems were those with more surface covered, those with cationic groups further away from silica surface and higher dendritic generation.Universidad de AlcaláMinisterio de Economía, Industria y CompetitividadComunidad de Madri

Prevalencia y riesgo anual de infeccion por tuberculosis en la población escolar de 7 años de edad de Ceuta

ResumenObjetivoConocer la prevalencia de la infección tuberculosa y el riesgo anual de infección en la población escolar de Ceuta.MétodoEstudio transversal. Se realizó la prueba de la tuberculina (2UT RT-23 Tween 80) a los niños de 7 años de edad escolarizados en Ceuta en 2008. Se consideraron positivos los niños no vacunados con una induración ≥5mm a las 72 horas.ResultadosSe estudiaron 612 niños. La prevalencia de la infección fue del 0,98% (intervalo de confianza del 95%, margen de error del 2,5%). Su distribución mostró diferencias entre las tres zonas de salud, y fue mayor en las zonas más deprimidas, donde llegó al 2,07%. El riesgo anual de infección fue del 0,15%.ConclusionesLa prevalencia de la infección es de las más altas de España, según los últimos estudios realizados. Los resultados no se corresponden con los datos epidemiológicos de tuberculosis de Ceuta, al tener en cuenta los casos importados.AbstractObjectiveTo determine the prevalence of tuberculosis infection and annual risk of infection in the school population of Ceuta.MethodA cross-sectional study was conducted. A tuberculin test (2UT RT-23 Tween 80) was given to 7-year-old schoolchildren in Ceuta in 2008. A positive result was considered as an induration of ≥5mm at 72hours in unvaccinated children.ResultsA total of 612 children were studied. The prevalence of tuberculosis infection was 0.98% (95% confidence interval with a 2.5% margin of error). The distribution showed differences among three health areas, and was greatest in the most deprived area (2.07%). The annual risk of infection was 0.15%.ConclusionsAccording to the most recent studies, the prevalence of tuberculosis infection in Ceuta is one of the highest of Spain. Our results do not agree with the epidemiological data for tuberculosis in Ceuta, which also includes imported cases

Dinuclear dialkoxo-bridged cyclopentadienylsiloxo titanium complexes

The dinuclear dialkoxo-bridged complexes [(TiCl)2(μ-O2L)(μ-{(η5-C5Me4SiMeO)2(μ-O)})] (O2L = 1,2-O2C2H41a, 1,2-O2C6H41b, 1,2-(OCH2)2C6H41c, O2SiPh21d) were obtained by reaction of [(TiCl2)2(μ-{(η5-C5Me4SiMeO)2(μ-O)})] (A) with the corresponding dilithium salt (1a) or diol (1b, 1c, 1d). Alkylation of 1a and 1b with ClRMg afforded [(TiR)2(μ-O2L)(μ-{(η5-C5Me4SiMeO)2(μ-O)})] (O2L = 1,2-O2C2H4, R = Me 2a, Bz 3a; O2L = 1,2-O2C6H4, R = Me 2b, Bz 3b). Addition of four equiv. of LiOiPr to A afforded [{Ti(OiPr)2}2(μ-{(η5-C5Me4SiMeO)2(μ-O)})] (4). Reaction of 1a with Al(C6F5)3 produced the elimination of the dialkoxo ligand to give [{TiCl(C6F5)}2(μ-{(η5-C5Me4SiMeO)2(μ-O)})] (5), whereas the same reaction of 1b with Al(C6F5)3 produced the oxo-alane adduct [(TiCl)2(μ-O2L)(μ-{(η5-C5Me4SiMeO)2(μ-O·Al{C6F5}3)})] (O2L = 1,2-O2C6H46) which was further transformed to give a mixture of 5 and [(TiCl){Ti(C6F5)}(μ-O2L)(μ-{(η5-C5Me4SiMeO)2(μ-O)})] (O2L = 1,2-O2C6H47). One benzyl group of complexes 3 was abstracted with E(C6F5)3 (E = B, Al) to give the monoionic compounds [Ti(TiBz)(μ-O2L)(μ-{(η5-C5Me4SiMeO)2(μ-O)})][BzE(C6F5)3] (O2L = 1,2-O2C2H4, E = B 8B, Al 8Al; O2L = 1,2-O2C6H4, E = B 9B), although 8Al was unstable in CD2Cl2 evolving to a mixture of compounds where [(TiBz)2(μ-Cl)(μ-{(η5-C5Me4SiMeO)2(μ-O)})][BzAl(C6F5)3] (10) was identified, and compound 9B was also unstable at ambient temperature. Polymerization of ε-caprolactone was only achieved with the tetraalkoxo compound 4. All of these complexes were characterized by NMR spectroscopy and 1a, 1b and 7 by X-ray diffraction studies

A framework for the development and maintenance of adaptive, dynamic, context-aware information services

This paper presents an agent-based methodological approach to design distributed service-oriented systems which can adapt their behaviour according to changes in the environment and in the user needs, even taking the initiative to make suggestions and proactive choices. The highly dynamic, regulated, complex nature of the distributed, interconnected services is tackled through a methodological framework composed of three interconnected levels. The framework relies on coordination and organisational techniques, as well as on semantically annotated Web services to design, deploy and maintain a distributed system, using both a top-down and bottom-up approach. We present results based on a real use case: interactive community displays with tourist information and services, dynamically personalised according to user context and preferences.Preprin